Anti-rust lubricating oil



ANTI-RUST LUBRICATING 01L 2,921,627 Patented Jan. 12, 1960 Z cabinet test conducted for 200 hours at 100 F. and 100 percent humidity with fresh saturated air being supplied at a rate between 1 and 1.5 complete changes per hour. Also, the hydrobromic acid tests are used to measure the 5 ability of rust-preventive lubricants to neutralize acidic Elmer W. Brennan, Carpentersville, 111., assignor to The corrosive atmospheres, particularly the acidic products Pure Oil Company, Chicago, 111., a corporation of present in exhaust gases. It has been found that known Ohio rust inhibitors which function to transform lubricating oils into rust-preventive lubricants for use under these No g gi gf g flf %f, 1957 10 storage conditions fail to provide the type of protection necessary to pass the static water drop corrosion test. 9 ClaimsvThis invention is based on the discovery of a new property of a class of compounds known as Tweens by the Atlas Powder Company, that is, the ability of this type This invention relates to improved anti-rust lubricating of compound to carry lubricating oil compositions oils and, more particularly, to lubricating oil composithrough the critical static water-drop corrosion test and tions which pass th; sltggigzwagg-lri rgp cdorro theriby meletbthe requirfiments fgr :11 rut1 inhillziitolrI for sion test designate as ate cran case n ricating .o 's,' spec ca y ass avy July 18, 1952. This test will hereinafter be referred to 9000 series crankcase lubricants. Tweens are polyoxyas Ttg: staticI water drop corrosion test. rt f 1 legilylene sorblitan estgis 01f1 fata acfidfi. A specific irorliluct 's app ication is acontinuation-in-pa o app ication own as weenas e o owing genera c ar- Serial Number 420,435, filed April 1, 1954, now abanacteristics: doned, by the present inventor.

The problem of protecting metallic equipment from Property Value atmospheric corrosion is one of long standing. A particularly acute problem is that of protecting internal Hydrophfle.Lipophfle 5 combustion engines and other equipment exposed to the FQIHJ 0 oilyliquidl- V1seos1ty.(cp.at 25 O.) 350-550. severely corrosive atmosphere encountered in coastal Spe ific gravity r 100.1 areas or On ship board and in many industrial areas. h P ggg The internal combustion engines used in military equip- 3 if i f I ment are often subjected to long periods of storage or exposure to corrosive environments during transportarTendS tovgelon tandingtion and must be protected. During operation these; Tween is a nofidonic surface acfive agent The englnes are often exposed to corrosive atmospheresand; pro-party of vhydmphflHipophile balance is an empirical i exh'ciust gases therefmmi especially from number assignedby The Atlas Powder Company to their engines produce corroslve.atmosliheres which. surface-active agents to represent the relative oil or water tenously affect metal Parts.W1fl.1 which, they 6.0mm m afiinity ofthe material. An agent having a hydrophilef Under emergericy slmatlon? sea Water 13 some lipophile balance of about 2.0 to 9.0 is classifiable as tunes used as a coolant 1n these engines and every effort 4O lipophflic I (Oi1 1iving) A agent having a hydrophilebe made to protect the metal parts as long as lipophilejbalance of..1,5.018.0 is designated as hydrophiposslble lic (water-living). Tween 81 is intermediate in regard Many techniques and compositions haVe been proposed this property, As to the solubility at in Various to protect metal Surf'fwes .fmin corroslon the use agents, 'the following information is available: Tween of removable Protecnv? coatmgs 9 as shishmg 001.117 81 is dispersible in distilled water, hard water, 5% pounds or rust-preventive compositions classified as 011$ H2504, 5% Na-OH, Nazsobiand 5% A1C13 In new and greases. Most of these compositions are intended for use in the metallic equipment during periods of agueolis i. Y 13 generally Soluble. storage as in gun barrels and breeches, metal containers, dlsperslble, requmng In some? Instances the use of hlgh mashing, in idle status, finished machine parts in Stop concentrations or careful ad ustment of the concentraage, and emergency equipment used during wartime or tlonin stock piles. For these purposes the compositions are Reactlens Showlllgthe Preparation of y generally screened by means of the well-known humidity be represented as follows! (I) CHPOH HOCH-CHOH HC-OH -H2O V C a CHCHOH H Anhydrization \0/ H H HG-OH Sorbitan H -OH Hr-OH l RCOOH (Fatty acid) Sorbitol HO-CHCHOH NCHr-CHz-i-C 2 CHOHCH2OOCR H l 1 Sorbitanester where R is the residue of a long-chain fatty acid such as oleic, lauric, palmitic or stea-ric, N=n +n +n and indicates the number of moles of ethylene oxide and n 22 and n, are any whole numbers from 1 to 7, inclusive.

' In Tween 81 RCOOH is oleic acid, N hasja value of '3 to 6, and accordingly, n n2 and 11 have values of l to 4 and may be the same or different. One skilled in the art will know that the anhydrization ofsorbitol in the above reaction is shown to involvethe hydrogen attached to the first carbon atom and the hydroxyl group on the 5th carbon atom. This reaction, as is known, may involve the hydrogen of the first carbon ,atOmof the sorbitol molecule and the hydroxyl group'of the fourth carbon atom in which event an ether ring having five carbon atoms results and the subsequentrea'ction with fatty acid and ethylene oxide resultsina product having the following formula: r

.. Compounds of both Formula I and Formula II are contemplated by this invention and'in fact are present as a complex mixture in the product known as' Tween 81. Increases 'in the amountsof ethylene oxide used in the reaction to the point where vN has a value of 7 to results in a product known as Tween 80 which for purposes of this invention is equivalent to Tween 81, being also polyoxyethylene sorbitan monoleate. Tween 80" has the same corrosion-inhibiting properties as Tween 81 as far as the purposes of this invention are concerned. These products are generally used to form emulsions, their respective abilities in this, regard, as measured by the interfacial surface tensions in dynes at C., being equivalent at concentrations of 0.1 weight percent and varying at lesser and greater'concentrations.

Tween 80 has an HLB factor of 15.0.and'is an oily liquid, having a viscosity (cp. at 25 C.) of 350-550,

a fsp.'gr. of 1.06-1.10, flash point 605 F., fire point of 645 F. and is a lemon-yellow color. The chemical name of polyoxyethylene sorbitan monoleate will be used in the balance of the specification and claims to mean either or both Tween 80 and Tween 81" and mixtures of same having either a 4 carbon atoms ether ring, ora 5 carbon atom ether ring, or both, as indicated heretofore. Although the invention will be demonstrated by reference to experiments using Tween 81 the invention will apply to polyoxyethylene sorbitan fatty esters broadly, regardless of the number of ethylene oxide groups reacted with each molecule of the ether-ester.

Accordingly, a primary object of this invention is to provide a lubricating composition which meets the requirements of the static water-drop corrosiontest MIL-v P-17272 (SHIPS), July 18, 1952. 7

Another object of the invention is to provide a lubricating composition which meets the engine performance requirements of M.S. 9030 oil (MIL-L-9000A), and also 7 the static water-drop test, by including in said composition a minor proportion of,v polyoxyethylene sorbitan ester of a fatty acid, particularly the. monoleate ester.

Other objects and advantages of the invention will become apparent as the description thereof proceeds.

To demonstrate the invention, a numberof known rust inhibitors were tested in a base mineral oil composition fortified with a detergent-inhibitor and a commercial corrosion inhibitor. The base or blankoil consisted of:

92.0 weight percent intermediate V.I. oil (200 vis.

neutral).

5.4 weight percent of a detergent inhibitor consisting of a mixture of 3.44 weight percent mineral lubricating oil, 1.35 wt. percent of barium diisobutyl phenol sulfide and 0.61 wt. percent of calcium petroleum sulfonate.

2.6 weight percent zinc hexyl dithiophosphate.

This base mineral oil composition so fortified meets the US. Navy engine performance requirements of M.S. 9030 oil (MIL-L-9000A) using a GM 71 engine. The zinc hexyl dithiophosphate is a commercial corrosion inhibitor which in itself or in combination with the detergent-inhibitor does not pass the static Water-drop corrosion test, but is used to meet the other anti-corrosion properties necessary to qualify the base composition to meet the M.S. 9030 oil requirements, which tests include bearing corrosion tests, etc. These addends are subsequently further defined.

The results of these experiments are set forth in the following table wherein blend No. 1 is the base oil just described.

TABLE I Statzc water drop COIIOSZOIL test Cone. In Time for No. Additive Percent u Formation Blank 24 hours Zinc naphthcnate 0. 15 48 hours 0 0 075 Do. Proprietary inhibitor A 0. 04 Do. Proprietary inhibitor B 0. 08 Do. Barium petroleum sulfonate. 0. 10 12 hours do O. 20 Do do 0.30 Do.

Organic phosphate. 0. 10 Stain at 48 hours Barium petroleum sulfonate 0. 20 48 hours. d0 0. 40 Do. Sorbitan monoleate. 0. 25 Do. Glycerol monoleate 0.25 Do. Polyoxyethylene sorbitan monoleate 0. 25 Stgin at-. 96

ours

1 Specimen was stained with surface disturbed. 2 Specimen was stained with no surface disturbances.

An M.S. 9030 oil should show no rust at the end of 96 hours testing. In addition, an M.S. 9030 oil must have a viscosity at 210 F. of 58 to 70 SUS, a flash point of about 390 F. minimum, and a maximum pour point of about 10 F. The procedure in MIL-1 47272 (SHIPS), July 18, 1952, comprises subjecting a io -inchthick, cold-rolled, steel sheet (SAE 1020) specimen shaped as an equilateral triangle to dimpling at its center to a depth of 0.110 inch. The dimple side is thoroughly polished with fine sand paper, and cleaned with C.P. benzene and petroleum ether. After cleaning, the specimen is'quickly immersed in the'oil sample with the concave side of the dimple uppermost. The container contai ing the test oil and specimen is then placed in an oven at l40i2 F. for one hour. After this, the container and contents are removed from the oven and a drop of water (0.2 ml.) is placed in the oil so as to rest in the shallow depression or dimple in the steel specimen by using a clean hypodermic syringe. The container is then covered with a glass cover, stored in the oven at 140:2" F., and observed daily for signs of failure, that is, the first sign of rust which definitely increases in intensity on the next day.

fied by other addends or not, through the static waterdrop corrosion test. The preferred compounds for this purpose are the monoleate esters which are known as Tween 80 and Tween 81, the latter compound being used to demonstrate the invention by blend No. 14.

The amount of the sorbitan derivativesused may vary somewhat within the prescribed limits depending on the overall composition and the oxidation-detergent or other addends present therein. In general, about 0.2 to'0.40 weight percent of polyoxyethylene sorbitan monoleate has been found to satisfactorily carry the composition through this severe rust test. About 0.2 weight percent is the minimum that will give assured protection and quantities over about 0.40 do not show any detectable decrease in the degree of staining.

The oil compositions intended by this invention may inclued other addends such as thickeners, V.I. improvers, oiliness agents, pour-point depressants, other anti-oxidants and other well-known types of addends, or may comprise a mineral lubricating oil and the polyoxythylene sorbitan monoleates alone in the amounts specified. Although this invention is limited to compositions passing the static Water-drop corrosion test designated as MIL- P-l7272 (SHIPS), it is not limited to the type of oil used in the experiments. Any mineral lubricating oil may be used whether obtained from Mid-Continent, Pennsylvania Coastal, or Texas crudes. The lubricating oil may be a light or heavy oil of the solvent-refined or conventionally-refined variety. The invention should be distinguished from the prior art which shows the use of sorbitan monoleate as a corrosion inhibitor in oils by means of the humidity cabinet test, or other tests using a corrosive atmosphere of a haloacid, since there is no relationship or correlation between compositions which pass the cabinet test and the problem confronting one in relation to the critical static water-drop corrosion test, a particularly difficult species of corrosion test. Other specific examples of compositions of this invention are set forth in the following table:

TABLE II Composition (Wt. percent) Constituent Blend No 16 14 17 Mineral llubricating oil (200 vis.

The detergent-inhibitor used in the compositions of this invention are described in United States Patent 2,379,241 by McNab and U.S. Patent 2,761,845 by Rogers. Broadly, this addend may comprise an oil-soluble metal salt having the general formula,

where M is a metal, preferably a divalent metal, cobalt, barium, calcium, aluminum, zinc, magnesium, cadmium, tin, lead, chromium, manganese and nickel; Y is a member of the right-hand side of group VI of the periodic table of elements, as oxygen or a member of the sulfur family; Ar is an aromatic nucleus such as benzene, or a condensed ring nucleus such as naphthalene, anthracene, etc.; Z is sulfur, selenium or tellurium; x is an integer of from 1 to 5, preferably 1 or 2; Q is an organic group which may be identical with the part of the com, pound which is on the left side of Z, or a group having a somewhat similar type of structure, or it may be a hydrocarbon group such as amyl, octadecyl, or aralkyl as benzyl, or aryl as tolyl; and R represents one or more hydrocarbon groups such as alkyl, or alkenyl, e.g., amyl, octyl, octenyl, etc., or cycle-aliphatic, e.g., cyclohexyl. Examples are the cobalt or barium salts of hydroxy tertiary-amyl phenyl sulfide, and the cobalt or barium salts of hydroxy diisobutyl phenyl sulfide. In place of the calcium petroleum sulfonate, any oil-soluble metal salt of an acidic organic compound may be used, i.e., the mixed aluminum-calcium soap of acids obtained in the oxidation of sweater oil, or nickel oleate. In general, from about 0.01 to 6.5 weight percent of the finished addend containing about 63.75 wt. percent of a mineral lubricating oil, 25.0% of the barium salt and about 11.25% of the calcium petroleum sulfonate is used. A species of this addend sold under the trade name of Paranox 65, has the following properties:

' The zinc hexyl dithiophosphate may be replaced with I other commercial addends designed for this purpose, such as zinc or cadmium alkyl dithiophosphates including zinc heptyl dithiophosphate, cadmium heptyl dithiophosphate, zinc octyl dithiophosphate, cadmium octyl dithiophosphate, etc.

What is claimed is:

1. A lubricating oil composition consisting essentially of a major portion of a mineral lubricating oil, a small amount of a polyvalent metal salt of an alkyl phenol sulfide selected from the group consisting of the barium salt of diisobutyl phenol sulfide, the cobalt salt of diiso butyl phenol sulfide, the barium salt of tertiary amyl phenol sulfide, and the cobalt salt of tertiary amyl phenol sulfide, a small amount of calcium petroleum sulfonate, a small amount of a polyvalent metal salt of an alkyl dithiophosphate selected from the group consisting of zinc hexyl dithiophosphate, zinc heptyl dithiophosphate, zinc octyl dithiophosphate, cadmium heptyl dithiophosphate, and cadmium octyl dithiophosphate, and at least about 0.2 weight percent of a polyoxyethylene sorbitan monofatty acid ester containing from 3 to 6 moles of ethylene oxide per molecule wherein the fatty acid esterifying group is selected from the group consisting of oleate, laurate, palmitate and stearate groups.

2. A lubricating composition in accordance with claim 1 in which said polyvalent metal salt of an alkyl phenol sulfide is the barium salt of diisobutyl phenol sulfide.

3. A lubricating composition in accordance with claim 1 in which said polyvalent metal salt of an alkyl dithiophosphate is zinc hexyl dithiophosphate.

4. A lubricating composition in accordance with claim 1 in which said polyoxyethylene sorbitan mono-fatty acid ester is polyoxyethylene sorbitan monoleate.

5. A lubricating oil composition characterized by its ability to meet the requirements of an MS. 9030 oil and pass the static water-drop corrosion test designated as MIL-P-17272-SI-IIPS, consisting essentially of about 91 weight percent of a mineral lubricating oil, about 5.4 weight percent of a detergent-inhibitor consisting of the following:

(1) About 3.44 weight percent of a mineral lubricating oil carrier.

(2) About 1.35 weight percent of a phenol sulfide salt selected from the group consisting of the barium salt of diis'obutyl phenol sulfide, the cobalt 'salt of diisobutyl phenol sulfide, the barium salt of tertiary amyl phenol sulfide, and the cobalt salt of tertiary amyl phenol sulfide and I I (3) About 0.61 weight percent of calcium petroleum sulfonate,

about 2.6 weight percent of an alkyl dithiophosphate salt selected from the group consisting of zinc hexyl dithiophosphate, zinc heptyl dithiophosphate, zinc octyl dithiophosphate, cadmium heptyl dithiophosphate, and -cadmium octyl dithiophosphate and between about 0.2 and 0.4 weight percent of polyoxyethylenesorbitan monofatty acid ester containing from 3 to 6 moles of ethylene oxide per molecule wherein the fatty acid portion is selected from the group of ole'ate, laurate, palmitate and stearate groups. I

6. A lubricating composition in accordance with claim 5 in which said phenol sulfide salt is the barium salt of diisobutyl phenol sulfide.

7. A lubricating composition in accordance with claim 5 in which said alkyl dithiophosphate salt is zinc hexyl dithiophosphate.

8. A lubricating composition in accordance with claim 5 in which said polyoxyethylene sorbitan mono fat'ty acid ester is polyoxyethylene sorbitan monol'ea'te.

9. A lubricating oil composition, characterized by its ability to meet the requirements of an MS. 9030 oil and pass the static water-drop corrosion test designated as MIL-'P-172 72 SHIPS, comprising about 91 weight percent of a mineral lubricating- 'oil, about 5.4 weight percent of a detergentdnhibitor consisting of about 3.44 weight percent of a mineral lubricating oil, about 1.35 weight percent of the barium salt of diisobutyl phenol sulfide and 0.61 weight percent of calcium petroleum sulfonate, about 2.6 weight percent of zinc hexyl dithiophosphate and between about 0.2 to 0.4 weight percent of polyoxyethylene sorbitan monoleate containing from 3 to 6 moles of ethylene oxide per molecule.

References Cited in the file of this patent UNITED STATES PATENTS 2,470,537 Waugh 'May 17, 1949 7 2,479,424 I Sproule et al. Aug. 16, 1949 20 2,560,202 Zimmer et al. July 10, 1951 2,565,403 Sproule et al. Aug. 21, 1951 Wilm., Del., 1948; Table I (facing page 26) and page 29. 

1. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PORTION OF A MINERAL LUBRICATING OIL, A SMALL AMOUNT OF A POLYVALENT METAL SALT OF AN ALKYL PHENOL SULFIDE SELECTED FROM THE GROUP CONSISTING OF THE BARIUM SALT OF DISOBUTYL PHENOL SULFIDE, THE COBALT SALT OF DISOBUTYL PHENOL SULFIDE, THE COBALT SALT OF TERTIARY AMYL PHENOL SULFIDE, AND THE COBALT SALT OF TERTIARY AMYL PHENOL SULFIDE, A SMALL AMOUNT OF CALCUIM PETROLEUM SULFONATE, A SMALL AMOUNT OF A POLYVALENT METAL SALT OF AN ALKYL DITHIOPHOSPHATE SELECTED FROM THE GROUP CONSISTING OF ZINC HEXYL DITHIOPHOSPHATE, ZINC HEPTYL DITHIOPHOSPHATE, ZINC OCTYL DITHIOPHOSPHATE, CADMIUM HEPTYL DITHIOPHOSPHATE, AND CADMUIM OCTYL DITHIOPHOSPHATE, AND AT LEAST ABOUT 0.2 WEIGHT PERCENT OF A POLYOXYETHYLENE SORBITAN MONOFATTY ACID ESTER CONTAINING FROM 3 TO 6 MOLES OF ETHYLENE OXIDE PER MOLECULE WHEREIN THE FATTY ACID ESTERIFYING GROUP IS SELECTED FROM THE GROUP CONSISTING OF OLEATE, LAURATE, PALMITATE AND STEARATE GROUPS. 